Flashcards in Lecture 34: Photosynthesis-light reactions Deck (10)
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1
what initiates light reactions in photosynthesis?
absorbance of light
2
consequence of electron transfer reactions in light reactions?
1) production of QH2 or NADPH (NADH)
2)translocate H+ and generate a proton gradient across a membrane-used for ATP synthesis
3)in cyanobacteria and plants, O2 is produced from H20
3
why is it called Dark reactions
don't require light
4
Subsequent to the light reactions.... dark reactions...
-biosynthesis that uses the ATP and NADPH to fix CO2 as 3-phosphoglycerate
-3-phosphoglycerate is used then to make C4 to C7 sugars
5
What wavelength does visible light contain?
700nm (red) to 400 nm (dark blue)
6
Types of Photosystems
PS II
PS I
Complex PsI and PSII
PS1 + PSII
7
PS II
-in purple and green filamentous bacteria
-type II reaction center with P870 chlorophyll
-works with cytochrome bc1 complex in a cyclic system
-There is a H+ translocation but not net production of NADPH
8
PSI
-in green sulfur bacteria
-type 1 reaction center with P700 chlorophyll
-works either with cytochrome bc complex in a cyclic system without net production of NADPH
OR
with an electron done such as H2S or S2O32- with net production of NADPH
9
Complex PSI + PSII
in cyanobacteria
-photosystems act in series
-works with cytochrome bf complex
-organisms use H2O as source of electrons to reduce the primary pigment in PSII with a net production of NADPH
10
